Obesity is classified as primary obesity (simple obesity) and secondary obesity (symptomatic obesity) according to its cause. The cause of primary obesity is thought to include the excess energy intake (e.g., overeating), energy under consumption (e.g., lack of exercise) and lower heat production. Currently, over 90% of obesity is primary obesity. When this primary obesity is developed and the condition is kept, it causes various health problems. On the other hand, secondary obesity results from some underlying disease. The Examples of the secondary obesity include endocrine obesity, hypothalamic obesity, hereditary obesity, obesity caused by a medicament and the like. Obesity triggers lifestyle-related diseases and obese people is susceptible to complications such as diabetes, hypertension, hyperlipemia, coronary atherosclerosis (angina or myocardial infarction), gout, cholelithiasis, fatty liver, infertility, osteoarthritis and the like.
The basic treatment for obesity is a combination of diet therapy and exercise therapy. However, this has a limitation and drug therapy is expected to be effective especially for morbid obesity.
Y5 receptor, which is a subtype of Neuropeptide Y (hereinafter referred to as NPY) receptor, at least involves in the feeding behavior and its antagonist is expected as an anti-obesity agent (Non-patent Document 1).
Amine derivatives having sulfonyl group and similar structures to compounds for this invention and exhibiting NPY Y5 receptor antagonistic activity are disclosed in Patent Document 1, 2, 3, 4 and the like. Amide derivatives having sulfonyl group and exhibiting NPY Y5 receptor antagonistic activity are disclosed in Patent Document 5, 8, 9, 10 and 11. Derivatives having sulfonyl group and exhibiting NPY Y5 receptor antagonistic activity are disclosed in Patent Document 12. The structures of these compounds are different from those of the compounds for this invention.
Furthermore, although compounds having similar structures to compounds for this invention are disclosed in Patent Document 6, 7, 13, 14 and the like, the activities of their compounds are quite different from those of the compounds for this invention. These documents do not disclose that their compounds are useful as an anorectic or anti-obesity composition and do not suggest this invention.    [Non-patent Document 1] Peptides, Vol. 18, 445 (1997)    [Non-patent Document 2] European Journal of Medicinal Chemistry, 2006, 42(4), pp. 463-470    [Patent Document 1] WO01/002379    [Patent Document 2] WO00/064880    [Patent Document 3] WO99/055667    [Patent Document 4] WO00/068197    [Patent Document 5] WO01/037826    [Patent Document 6] WO2006/014482    [Patent Document 7] WO2005/097738    [Patent Document 8] WO97/20823    [Patent Document 9] US2006/293341    [Patent Document 10] WO2007/002126    [Patent Document 11] WO2006/001318    [Patent Document 12] WO2005/080348    [Patent Document 13] US2007/060598    [Patent Document 14] WO2005/121107    [Patent Document 15] WO2007/125952    [Patent Document 16] WO2008/134228